1. Technical Field
The present invention relates to a method for reducing carbon dioxide and a device used therefor.
2. Description of the Related Art
U.S. Pat. No. 8,696,883 discloses a method for reducing carbon dioxide. In this method, an anode formed of a nitride semiconductor is irradiated with light to reduce carbon dioxide on a cathode electrode. The method disclosed in U.S. Pat. No. 8,696,883 does not need an external power supply such as a solar battery or a potentiostat. In other words, in the method disclosed in U.S. Pat. No. 8,696,883, the energy to be supplied to reduce carbon dioxide is only light.
Japanese Patent Application laid-open Publication No. 2003-024764 discloses a gas generator. In Japanese Patent Application laid-open Publication No. 2003-024764, an anode is irradiated with light to produce a hydrogen gas on a cathode electrode. The anode disclosed therein comprises a first n-type nitride semiconductor layer formed of InGaN, a p-type nitride semiconductor layer formed of GaN, and a second n-type nitride semiconductor layer formed of GaN.
WO 2006/082801 also discloses a gas generator using a nitride semiconductor. In the paragraph 0026 of WO 2006/082801, it is described that the nitride semiconductor may be a stacked structure of plural AlGaInN layers each having a different composition. Furthermore, it is described that the stacked structure is a stacked structure of n-type-p-type-n-type from the front surface side in a case where the nitride semiconductor is used as an anode.